--[[--
用指定字符或字符串分割输入字符串，返回包含分割结果的数组
local input = "Hello,World"
local res = string.split(input, ",")
-- res = {"Hello", "World"}

local input = "Hello-+-World-+-Quick"
local res = string.split(input, "-+-")
-- res = {"Hello", "World", "Quick"}

@param string input 输入字符串
@param string delimiter 分割标记字符或字符串
@return array 包含分割结果的数组
]]
function string.split(input, delimiter)
    input = tostring(input)
    delimiter = tostring(delimiter)
    if (delimiter=='') then return false end
    local pos,arr = 0, {}for st,sp in function() return string.find(input, delimiter, pos, true) end do
        table.insert(arr, string.sub(input, pos, st - 1))
        pos = sp + 1
    end
    table.insert(arr, string.sub(input, pos))
    return arr
end

--[[--
去除输入字符串头部的空白字符，返回结果
local input = "  ABC"
print(string.ltrim(input))
-- res ABC，输入字符串前面的两个空格被去掉了

空白字符包括：
-   空格
-   制表符 \t
-   换行符 \n
-   回到行首符 \r
@param string input 输入字符串
@return string 结果
@see string.rtrim, string.trim
]]
function string.ltrim(input)
    return string.gsub(input, "^[ \t\n\r]+", "")
end
--[[--
去除输入字符串尾部的空白字符，返回结果
local input = "ABC  "
print(string.ltrim(input))
-- res ABC，输入字符串最后的两个空格被去掉了


@param string input 输入字符串
@return string 结果
@see string.ltrim, string.trim

]]
function string.rtrim(input)
    return string.gsub(input, "[ \t\n\r]+$", "")
end
--[[--
去掉字符串首尾的空白字符，返回结果
@param string input 输入字符串
@return string 结果
@see string.ltrim, string.rtrim
]]
function string.trim(input)
    input = string.gsub(input, "^[ \t\n\r]+", "")
    return string.gsub(input, "[ \t\n\r]+$", "")
end

--[[--
将字符串的第一个字符转为大写，返回结果
local input = "hello"
print(string.ucfirst(input))
-- res Hello
@param string input 输入字符串
@return string 结果
]]
function string.ucfirst(input)
    return string.upper(string.sub(input, 1, 1)) .. string.sub(input, 2)
end--[[--
计算 UTF8 字符串的长度，每一个中文算一个字符
local input = "你好World"
print(string.utf8len(input))
-- res 7

@param string input 输入字符串
@return integer 长度
]]
function string.utf8len(input)
    local len  = string.len(input)
    local left = len
    local cnt  = 0
    local arr  = {0, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc}
    while left ~= 0 do
        local tmp = string.byte(input, -left)
        local i   = #arr
        while arr[i] do
            if tmp >= arr[i] then
                left = left - i
                break
            end
            i = i - 1
        end
        cnt = cnt + 1
    end
    return cnt
end

----过滤出规范字符 只保留汉字、数字、字符
function string.filterSpecChars(s)   
    local ss = {}    
    local k = 1    
    while true do        
        if k > #s then break end        
        local c = string.byte(s,k)        
        if not c then break end        
        if c<192 then            
            if (c>=48 and c<=57) or (c>= 65 and c<=90) or (c>=97 and c<=122) then                
                table.insert(ss, string.char(c))            
            end            
            k = k + 1        
        elseif c<224 then            
            k = k + 2        
        elseif c<240 then            
            if c>=228 and c<=233 then                
                local c1 = string.byte(s,k+1)                
                local c2 = string.byte(s,k+2)               
                if c1 and c2 then                    
                    local a1,a2,a3,a4 = 128,191,128,191                    
                    if c == 228 then a1 = 184                    
                    elseif c == 233 then 
                        a2,a4 = 190,c1 ~= 190 and 191 or 165                    
                    end                    
                    if c1>=a1 and c1<=a2 and c2>=a3 and c2<=a4 then                        
                        table.insert(ss, string.char(c,c1,c2))                    
                    end                
                end            
            end            
            k = k + 3        
        elseif c<248 then            
            k = k + 4        
        elseif c<252 then            
            k = k + 5        
        elseif c<254 then            
            k = k + 6       
        end    
    end    
    return table.concat(ss)
end

--[[--
将数值格式化为包含千分位分隔符的字符串
print(string.formatnumberthousands(1924235))
-- 输出 1,924,235

@param number num 数值
@return string 格式化结果
]]
function string.formatnumberthousands(num)
    local formatted = tostring(checknumber(num))
    local k
    while true do
        formatted, k = string.gsub(formatted, "^(-?%d+)(%d%d%d)", '%1,%2')
        if k == 0 then break end
    end
    return formatted
end
-- 判断utf8字符byte长度
-- 0xxxxxxx - 1 byte
-- 110yxxxx - 192, 2 byte
-- 1110yyyy - 225, 3 byte
-- 11110zzz - 240, 4 byte
local function chsize(char)
    if not char then
        print("not char")
        return 0
    elseif char > 240 then
        return 4
    elseif char > 225 then
        return 3
    elseif char > 192 then
        return 2
    else
        return 1
    end
end

-- 截取utf8 字符串
-- str:         要截取的字符串
-- startChar:   开始字符下标,从1开始
-- numChars:    要截取的字符长度
function string.utf8sub(str, startChar, numChars)
    local startIndex = 1
    while startChar > 1 do
        local char = string.byte(str, startIndex)
        startIndex = startIndex + chsize(char)
        startChar = startChar - 1
    end

    local currentIndex = startIndex

    while numChars > 0 and currentIndex <= #str do
        local char = string.byte(str, currentIndex)
        currentIndex = currentIndex + chsize(char)
        numChars = numChars -1
    end
    return str:sub(startIndex, currentIndex - 1)
end

--判断字符串是否为nil或““
function string.IsNilOrEmpty(str)
    if not str or str == "" then
        return true
    end
    return false
end